Recently, 3D broadcasting channels, 3D games, and 3D movies using 3D effects such as broadcasting, games, and movies receive attention, and the recently released home TVs or monitors support 3D stereoscopic video playback, thereby making it easy for the general public to see 3D stereoscopic images.
Such 3D stereoscopic images use a binocular parallax that occurs due to differences in the images of the left and right sides as the eyes of a person are separated by a distance of 6.5 cm, and in order to do this, two cameras spaced the same distance as the eyes of a person apart from each other capture images simultaneously, and the image captured through the left camera and the image captured through the right camera are reproduced on one monitor, and a user who wears a 3D glasses will see only the left image with the left eye and the right image with the right eye, so that it is possible for the user to feel a 3D feeling (perspective) as the user's brain is mistaken for viewing the left and right images reproduced at a high speed simultaneously.
Meanwhile, a method of reproducing such a 3D stereoscopic image may be largely divided into a method of wearing a glasses and a method of wearing no glasses, and the method of wearing a glasses may be divided into a shutter glass method and a polarizing method.
First, the shutter glass method is a method of rapidly reproducing only the left image in odd numbered pixels at 120 Hz and the right image in even numbered pixels at 120 Hz alternately through a monitor capable of reproducing 240 Hz, that is, 240 frames per second, and an infrared transmitter (emitter) in the monitor applies a signal to the 3D glasses, and in the 3D glasses, the processes of closing the right glass of the 3D glasses when the left image is reproduced and closing the left glass of the 3D glasses when the right image is reproduced are rapidly repeated, thereby allowing a user to have 3D feeling.
Next, in the polarizing method, by splitting horizontal scan lines by each column, only the left image is reproduced in the odd-numbered columns and only the right image is reproduced in the even-numbered columns, and only the odd-numbered columns are polarized in the left glass of the 3D glasses and only the even-numbered columns are polarized in the right glass of the 3D glasses, thereby allowing a user to have 3D feeling.
However, the conventional 3D stereoscopic effect using such a polarization method has a problem in that incident light has to be shielded according to a polarized component (vertical or horizontal) due to the characteristics of a polarization element and according thereto, the luminance of the incident light is lowered.
In order to solve such a problem, conventionally, a polarizing beam splitter (PBS) is used to split an incident light according to a polarized component and delay the phase of the split light through an optical switch element and a polarization rotator in order to allow each light to be a synthesized light composed of lights having the same type of polarized component, thereby preventing a decrease in brightness.
However, in such a conventional technique, the case of a liquid crystal (LC) panel used for an optical switch element has the following problems in 1) in order to selectively polarize vertical and horizontal lights, a structure of a plurality of overlapping LC panels should be provided and thus a thickness thereof becomes thicker, 2) the structure is complicated because all the characteristics that each LC panel has should be considered while a plurality of LC panels are overlapped with each other without separation, and 3) the luminance is reduced due to the use of a plurality of LC panels.
In addition, since the surface of the above-mentioned PBS forms the same coating layer in the conventional technique, as the incident angle of the light incident on the PBS becomes different from each other according to the central portion side and both-side end portions of the PBS, the performance of the PBS is significantly reduced toward the both-side end portions.
In addition, in order to compensate for the inherent viewing angle that an optical switch device has, an additional wide view film should be used, and the quality of an image is deteriorated due to the use of the wide view film.
Accordingly, in order to solve the problems of the conventional 3D stereoscopic image reproducing technology, the inventor invents a stereoscopic image display device for splitting the incident light into different lights according to polarized components, subsequently converting each light to have the same polarized component by selectively delaying the phase of each split light by a predetermined value through an on/off operation of an optical switch module, and projecting a synthesized light obtained by synthesizing the lights having the same polarized component on a screen so as to double the luminance on the screen.